EUVD-2026-56697
GHSA-q839-g6gr-9h5f
Severity by source
Sources disagree (Medium–Critical)AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Local vector with mandatory user interaction to open crafted document; no privileges required; read-only memory disclosure with no integrity or availability impact.
vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Out-of-bounds read in Microsoft Office Word allows an unauthorized attacker to disclose information locally.
AnalysisAI
Out-of-bounds read in Microsoft Office Word exposes potentially sensitive memory contents to local attackers when a victim opens a specially crafted document. Affected products span Microsoft Word 2016, Office 2019, Office LTSC 2021 and 2024, Office 365 for Mac, and Microsoft 365 Apps for Enterprise across both Windows and macOS platforms, with vendor-confirmed patches available. No public exploit code exists and CISA SSVC rates exploitation likelihood as none with only partial technical impact, making this a medium-priority patching item despite the High confidentiality score assigned by CVSS.
Technical ContextAI
The vulnerability is rooted in CWE-125 (Out-of-Bounds Read), occurring in Microsoft Office Word's document parsing engine. When processing a maliciously crafted Word file, the application reads memory beyond the bounds of an allocated buffer, potentially exposing adjacent memory contents such as heap metadata, stack data, or in-process application data. It is important to note that the intelligence tags list 'Buffer Overflow,' which is a distinct and more severe class (CWE-120/CWE-787 enabling write primitives); the authoritative CWE-125 classification confirms this is a read-only memory safety violation with no write capability implied. Affected CPE-identified products span both the Windows Office ecosystem (Word 2016, Office 2019, LTSC 2021/2024, Microsoft 365 Apps for Enterprise) and macOS-based Office suites (Office 365 for Mac, LTSC for Mac 2021/2024), indicating the vulnerable parsing code is shared across platform builds.
RemediationAI
The primary remediation is to apply the Microsoft-released patch. For Microsoft Word 2016 on Windows, upgrade to build 16.0.5565.1000 or later - this is the only Windows product line with an explicit confirmed fix build in available data. For all macOS-based Office products (Office 365 for Mac, LTSC for Mac 2021, LTSC for Mac 2024), upgrade to build 16.112.26081010 or later. For Office 2019, Microsoft 365 Apps for Enterprise, LTSC 2021, and LTSC 2024 on Windows, apply the latest cumulative update via Microsoft Update or at https://aka.ms/OfficeSecurityReleases, as explicit build numbers for these SKUs were not available in the sourced data. As compensating controls prior to patching, organizations should enforce Office Protected View via Group Policy (File > Trust Center > Protected View), which opens untrusted documents in a read-only sandbox and limits parser exposure - note this does not eliminate the vulnerability but reduces attack surface. Additionally, configuring email gateways to sandbox or block Word documents from untrusted external senders reduces delivery opportunity. Do not rely on the 'Buffer Overflow' tag to justify assuming write-primitive mitigations are needed; the OOB read nature limits direct exploitation pathways.
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Same weakness CWE-125 – Out-of-bounds Read
View allSame technique Buffer Overflow
View allShare
External POC / Exploit Code
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